Multiple circuit breaker assembly with common tripping



Nov. 29, 1966 i K. w. KLEIN 3,288,965

MULTIPLE CIRCUIT BREAKER ASSEMBLY WITH COMMON TRIPPING Filed Aug. 5, 1965 IN VENTOR. KEITH M ME/A/ BY fiw f y A TTOR/VE Y United States Patent 3,288,965 MULTIPLE CIRCUIT BREAKER ASSEMBLY WITH COMMON TRIPPING Keith W. Klein, Simsbury, Conn, assignor to General Electric Eompany, a corporation of New York Filed Aug. 5, 1965, Ser. No. 477,393 1 Claim. (Cl. 200116) The present invention relates to multiple electric circuit breakers, and more particularly to multiple circuit breakers made up of individually housed circuit breaker pole units, each having its own operating and tripping mechanism, and means for causing tripping of all such pole units of a given assembly when one unit trips.

Electric circuit breakers of the type described include, in each pole unit, a releasable member which is normally held by a latch member and biased toward tripped position. When released by the latch member, the releasable member causes automatic opening of the contacts of that particular pole unit. In order to cause automatic opening of adjacent pole units which form an operative assembly, a common trip bar is used, extending through the casings of all pole units. The releasable member of each pole is provided with a projection which strikes the common trip bar when the releasable member is released, and rotates it. Rotation of the common trip bar, in turn causes releasing movement of latch members of adjacent poles.

The operating mechanism used in such circuit breakers is usually of the over-center spring type. In such mechanisms, when tripping occurs, there is a limited amount of force acting on the releasable member tending to move it toward tripped position. If the releasable member engages the common trip member too soon in its tripping movement, it may be prevented from moving far enough to open the contacts of the circuit breaker.

In addition, the latch member of each of these circuit breakers commonly includes a magnetic means for causing tripping, with a relatively small air gap. The size of the air gap limits the movement of the latch member in tripping direction. Thus the common trip bar can move such latch members only a limited distance before its travel is arrested. If the circuit breaker contacts have not opened by such time, their opening movement may be prevented. In addition, normal manufacturing variations or tolerances have a substantial effect on the loading of the releasable member of the initiating pole unit, requiring extremely accurate manufacturing assembly operations and testing procedures. This adds substantially to the cost of manufacture of such circuit breakers.

It is an object of the present invention to provide a multiple circuit breaker of the type described in which movement of the releasable member of the initiating pole is not obstructed in its early travel by the loading of latch forces of adjacent circuit breakers. It is another object of the invention to provide a multiple circuit breaker of the type referred to in which the dimensional relationship of the parts is not extremely critical, thereby greatly facilitating the assembly and testing of such circuit breakers.

It is another object of the invention to provide a multiple circuit breaker of the type described in which the parts are not sensitive to the accumulation of manufacturing variations or tolerances.

In accordance with the invention, a multiple circuit breaker assembly is provided including at least two circuit breaker units or pole, each including a mechanism having a releasable member which is biased toward tripping position, and latch means normally restraining the releasable member. A common trip bar is also provided extending between the two poles of the circuit breaker.

lCC

Means is also provided at each pole of the circuit breaker whereby rotation of the common trip bar causes movement of the latch member of that particular pole. In accordance with the invention, the latch member at each pole includes a resilient member which is engaged by the member movable by the common trip bar so that force is stored in the resilient member which operates to move the latch member to trip position when the accumulated force is sufficient. This allows for considerable variation in the dimensional relationship of the parts and yet does not present any positive obstacle to motion of the parts to trip position.

The invention will be more fully understood from the following detailed description, and its scope will be pointed out in the appended claim.

In the drawings,

FIGURE 1 is a side elevation view of an electric circuit breaker incorporating the invention, the side nearest the observer being removed to show the parts, the parts being shown in the normal off condition;

FIGURE 2 is a fragmentary view showing portions of the mechanism of the circuit breaker of FIGURE 1, the parts being shown in tripped condition;

FIGURE 3 is a perspective view of a multi-pole circuit breaker assembly incorporating the invention;

FIGURE 4 is an exploded view of the circuit breaker assembly of FIGURE 3, showing particularly the common trip bar assembly;

FIGURE 5 is an exploded perspective view showing portions of the multi-pole circuit breaker assembly of FIGURE 3;

FIGURE 5A is perspective view of one of the elements of the common trip assembly of the multi-pole circuit breaker assembly of FIGURE 3;

FIGURES 6, 7, and 8, are fragmentary views of another embodiment of the invention.

Referring to the drawings, the invention is shown as incorporated in an electric circuit breaker comprising a generally rectangular insulating casing including a body portion 10 having recesses and supporting formations to carry the parts. A cover 10' is also provided to close the open side of the casing (see FIGURE 3). The invention is shown as used in conjunction with a circuit breaker operating mechanism including manually operable handle member 11 which is pivotally supported in the casing 10 and cover (not shown) by means of oppositely extending integral hub portions 12. The handle 11 includes a pair of spaced depending extensions 13 straddling a generally planar releasable member 14 which is pivotally supported in the casing and cover by means of a pivot pin 15. A movable contact arm 16 carries movable contact 17 on its lower end and has its upper end bifurcated to provide a pair of spaced leg portions 18 by which the contact arm 16 is pivotally supported on the depending portions 13 of the handle 11 at pivot bearings 19. A tension-type operating spring 20 is connected between the contact arm 16 and a hole 21 of the releasable member 14. A stationary contact 4 is carried by a projecting tang 5 of a socket member 6 which is adapted to receive a blade-type contact member, not shown, by plugin frictional engagement.

Motion of the handle 11 between on and off positions as indicated in FIGURE 1 moves the pivot point 19 of the contact arm 16 back and forth across the line of action of the tension spring 20 to move the contact arm 16 between open and closed circuit positions as indicated in solid and dotted lines respectively in FIGURE 1 with a snap action.

The releasable member 14 is normally supported in the position shown in FIGURE 1 by latch means to be described. When the member 14 is released by such latch means, the tension spring 20, pulling downwardly on the releasable member 14 at the hole 21, rotates the releasable member 14 clockwise about its pivotal support 15, moving the upper end of the spring to the right as viewed across the pivotal support 19 of the contact arm 16. This reverses the bias of the tension spring 2% on the contact arm 16 and moves it to open circuit position. This action takes place even though the handle 11 may be manually held in the on position. The parts moving to tripped position as shown in FIGURE 2.

In order to rest the mechanism following tripping, the handle 11 is rotated to the off position, during which motion, the depending extensions 13 engage opposite end portions of a reset pin 23 carried by the releasable member 14 and move it counterclockwise to its relatched position.

The releasable member 14 is held in its normal or latched position by a combined armature-latch member 24 which is pivotally supported in the casing on integral pivot lugs 25. The armature-latch member 24 is biased clockwise about its pivotal support 25 in a latching direction by means of a compression spring 26 trapped in the casing. The armature-latch member 24 includes an integral outwardly bent latch portion 27 which engages the end 28 of the releasable member 14 as shown in FIGURE 1. A lower end portion 29 of the armature-latch member 24- is return-bent and is positioned to be engaged by the lower or movable end of an elongated bimetallic strip 30, the other end of Which is fixedly attached to one end 32 of a terminal strap 33. The terminal strap 33 is mounted on the insulating base 10 by a mounting screw 34, and carries a wire-connecting means 36 at its outer end.

A generally U-shaped magnetic field piece 37 is rigidly attached to the bimetallic strip 30 adjacent its movable end. The bimetallic strip 30 is connected by a flexible conductor 38 to the movable contact arm 16. The current path through the circuit breaker therefore is from the terminal 36 through the conducting terminal strap 33 to the bimetallic strip 30, to the flexible conductor 38, to the movable contact arm 16, the movable contact 17, the stationary contact 4 and finally to the line terminal or socket 6.

The operation of the trip mechanism is as follows. The flow ofexcess current through the bimetallic strip 36 generates heat therein which causes the strip 30 to warp so as to move the lower end thereof to the right as viewed in FIGURE 1. The lower end of the bimetallic strip 30 engages the return-bent end portion 29 of the armaturelatch member 24, rotating it counterclockwise about its pivot and withdrawing the latch member 27 from the releasable member 14.

Magnetic tripping occurs upon the passage of sufficient current through the bimetallic strip 30, which energizes the magnetic field piece 37, causing it to attract the armature-latch member 24 to it, withdrawing the latch member 27 in a similar manner.

In accordance with the invention, the circuit breaker unit just described is adapted to be used singly, or in multiples of two, three or more to provide two, three or more multi-pole-circuit breakers having common tripping means.

M ulzi-pole assembly and common tripping means In FIGURE 3, there is shown a two-pole circuit breaker comprising two single pole units 10A and 1GB. Each of the circuit breaker units NA and 10B is constructed as shown in FIGURE 1. For the purpose of facilitating common tripping action in a manner to be described, however, latch actuating member 4@ is provided (FIG. A), of insulating material, pivotally supported in the casing by means of integral trunnions 41. The latch actuating member 40 also includes a rectangular hole 42 extending transversely therethrough, and a cam surface 43.

The latch actuating members 40A, 40B, of each of the breakers A and 10B are interconnected by a common if}, trip bar 44 as shown particularly in FIGS. 4 and 5, which extends through holes 45A and 45B cut in the adjacent side walls of the breakers 10A and 10B. The operating mechanism of each of the breakers 10A and 10B, is as shown in FIGURE 2 (shown in the tripped position).

For the purpose of cooperating with the latch actuating member in a manner to be described, the armature-latch 24 is provided with a rectangular cut-out or window 24A, and an elongated resilient spring strip 45, as shown particularly in FIGURE 5. The spring strip 45 is attached to the armature-latch member 24 by suitable means, such as by welding or riveting. The armature-latch member 24 includes an upwardly-directed integral lug portion 248 extending upwardly from the lower ledge of the window 24A, against which the lower end of the spring strip 45 is biased as a stop. The lug portion 243 also acts as a stop, to limit the clockwise rotation of the latch actuating member 40. For the purpose of cooperating with the common latch actuating member 46, the releasable member 14 includes a shoulder portion 14A, see FIG- URES 1 and 2.

The operation of the invention will be understood first by reference to FIGURES 1 and 2. In FIGURE 1, the mechanism is shown in normal off condition. The on condition of the contact is shown in dotted lines. Upon release of the releasable member 14 of one pole unit mechanism, such as by movement of the bimetallic strip to the right as viewed, moving the armature-latch member to the right, the releasable member 14 is moved clockwise about its pivot 15 to cause automatic opening of the contact as previously described. As the releasable member 14 rotates clockwise, the shoulder 14A engages the cam surface 43 of the latch actuating member 40 and rotates the latch actuating member 40 counterclockwise about its pivotal supports 41, as shown in FIGURE 2. Rotation of the latch actuating member 40 counterclockwise carries with it the common trip bar 44, which in turn causes similar counterclockwise rotation of the adjacent common latch actuating member 40A. When the latch actuating member 40A is rotated in this manner, a projecting portion thereof 43A acts on the resilient strip member 45 to cause rotation of the armature-latch member of the adjacent breaker to cause it to trip. By this means, tripping of both poles the two pole breaker is assured when either pole trips.

It will be observed that the gap between the armaturelatch member 24 and the magnetic field piece 37, as shown in FIGURE 1, is relatively small. Also, it will be observed that rotation of the armature-latch member in counterclockwise direction about its pivotal supports 25 is limited by its engagement with the field piece 37. This in turn limits the amount of rotation permitted the latch actuating member 46. Ordinarily, therefor, the latch actuating member 40 could not rotate in its tripping direction more than the amount permitted by the travel of the armature-latch member 24. Since tripping of the adjacent circuit breaker requires adequate movement of the common trip members, extremely critical adjustment and spacing are ordinarily required to obtain such common tripping. In accordance with the present invention, however, the use of the resilient strip 45 permits the latch actuating member 40 to rotate in tripping direction a total amount greater than that which otherwise would be permitted by the armature-latch member '24. Thus, for example, as shown in FIGURE 2, after the armaturelatch member 24 has engaged the pole of the field piece 37, the latch actuating member 44 can continue to rotate, by the resilient movement of the end of the spring strip 45 with respect to the armature-latch member 24.

This arrangement also insures that the trip-initiating breaker 'mechanism will be able to complete its own tripping operation. It will be observed, for example, that with an extremely small magnetic air gap, rotation of the releasable member 14 clockwise about its pivotal support 15 might possibly be impeded by engagement of armature-latch member 24 with the field piece 37, which in turn blocks movement of the latch actuating member 40 and the releasable member 14. Since the resilient strip 45 moves with respect to the latch member 24, however, the latch member 40 is free to rotate to a further extent, thereby assuring tripping of the adjacent breaker.

It will be understood that it is immaterial which of the two breakers initiates the common tripping operation, the \functioning of the adjacent breaker being as described above.

In FIGURES 6-8 there is shown another embodiment of the invention in this [form of the invention, the resilient strip 145 includes a latch projection 145A, and the member 124 operates only as an armature member. The armature member 124 is also extended at the lower end and return-bent at 129 to provide an engagement with the bimetallic strip 130. The operation of this form of the invention is similar to that previously described, and is clearly shown in FIGURES 6 and 7.

While the invention has been shown in only two embodiments, it will be readily appreciated that many modifications thereof may readily be made, and it is therefore intended by the appended claim to cover all such modifications as fall within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

A multiple circuit breaker assembly comprising:

(a) a pair of circuit breaker pole units;

(b) means supporting said pole units in closely-spaced side-by-side relation;

(c) each of said pole units comprising a stationary contact, a movable contact, and manually operable mechanism for moving said movable contact between open and closed circuit positions with respect to said stationary contacts;

(d) said manually operable mechanism including a member releasable to cause automatic opening of said contacts;

(e) a latch member normally restraining said releasa le m m e (I) each of said pole units further comprising a latch actuating member;

( g) common trip means interconnecting said latch actuating members of said pole units and causing simultaneous movement thereof;

(h) means carried by said releasable member'- of one of said pole units engaging said latch actuating member of said one pole unit upon release of said releasa-ble member and causing movement of said latch actuating member;

(i) said movement of said latch actuating member of said one pole unit being transmitted to said latch actuating member of the other of said lpole units by said common trip means and moving said latch actuating member into engagement with said latch member of said other pole unit and causing release of said releasable member of said other pole unit;

(j) each of said latch members comprising a first, rigid, portion and a second, resilient, portion, said resilient portion being resiliently movable by said latch actuating member in releasing direction with respect to said rigid portion;

(k) each of said rigid portions of said latch members including a generally rectangular cut-out and said resilient portion comprising a resilient strip extending across at least part of said cut-out at one side of said latch member, said rigid portion further including an integral lug portion projecting into the general area of said out-out and acting as a stop [for said resilient strip .and also as a stop for movement of said latch actuating member in at least one direction.

References Cited by the Examiner UNITED STATES PATENTS 2,824,191 2/1958 Christensen ZOO-88 X 2,889,428 -6/ 1959 Kingdon et al. 200 116 2,996,589 8/ 1961 Myers 200'1 16 3,081,386 3/ 1963 Koenig et al. 200-116 3,089,933 5/1963 Locher 200-416 BERNARD A. GILHEANY, Primary Examiner. 

